Positive shut off valve that closes under certain pressure?

Positive shut off valve that closes under certain pressure?

I'm designing a system and I have to use two separate pressure sensors hooked up to the same line. The first is going to be a 500psi pressure transducer for a low pressure test (250psi) and the second is a 20k pressure transducer for the high pressure testing (10-15k). When I start the high pressure test I need to be able to have a valve or something that automatically shuts closed in front of the smaller transducer when the pressure becomes too high (say, 500psi) so that the transducer doesn't blow. This is also why it has to be a positive shut off valve.

I haven't found anything so far. I'm thinking it would basically be like a pressure relief valve but instead of releasing the pressure it just closes shut.

*Edit, sorry I forgot to mention this in a hydraulic system

Thanks in advance for any help.

RE: Positive shut off valve that closes under certain pressure?

I would use a 3-way valve that is set to isolate the transducer from the system and vent it back to the supply tank. That way if it leaks a little it just goes back to the tank (i.e., the transducer is on the always-on or upstream leg and the downstream leg cycles between the system and the tank).

If you REALLY want postitive energy isolation, you'll need three solenoid valves (two in series with a vent between them). I don't think that will really give you a better result than a 3-way valve, but it won't be worse.

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